The goal of this Mentored Clinical Scientist Development Award (K08) is to permit the Candidate to develop into an independent clinical investigator by pursuing a program of training and supervised clinical research in brain anatomic magnetic resonance imaging (MRI) of childhood bipolar disorder. Despite the well documented morbidity and dysfunction of childhood BPD, the disorder remains one of the most controversial topics in child psychopathology and as a consequence, among the least researched child psychiatric disorders. This controversy is largely nosological. There is no disagreement that these children exist. Yet, it is the absence of adequate scientific data on childhood BPD that has generated a vicious cycle of skepticism and absence of research. A leading factor that complicates the diagnosis of BPD in children is the frequent comorbidity with ADHD. The critical question is whether these children have ADHD, BPD or both disorders. The resolution of this question has important clinical implications. To this end, the applicant proposes a morphometric study aimed at disentangling the comorbidity of childhood BPD with ADHD. Four samples, consisting of twenty 6-16 year old children, will be studied: 1) children with both ADHD and BPD 2) children with ADHD, 3) children with BPD, and 4) healthy volunteers. The study tests four competing hypotheses to determine whether children with BPD+ADHD have morphometric findings, in conjunction with clinical correlates that are similar to children with ADHD, or children with BPD, or with children with both ADHD and BPD, or if they have unique findings. If funded, the proposed work will fill two gaps in the research literature: it will be 1) the largest neuroimaging study of childhood BPD and 2) the first MRI study that tests hypotheses about the relationship between ADHD and BPD. By shedding light on the nosologic debate, this work will have implications for the diagnosis and treatment of these children. In addition, the Candidate will train in Clinical Research Methods in Child Psychiatry (20 percent effort) under the sponsorship of Joseph Biederman, M.D. (co-mentor), Professor of Psychiatry at Harvard Medical School and Verne Caviness, M.D. (co-mentor), Professor of Pediatric Neurology at Harvard Medical School, allowing her to master the methodology of morphometric studies in childhood BPD, emphasizing the assessment of psychopathology in the children and the evaluation of their MRI scans. Dr. Stephen Faraone, Associate Professor of Psychiatry, will serve as a consultant regarding data base management and data analysis and regarding Formal Didactic Training (20 percent effort) in biostatistics courses at the Harvard School of Public Health. By allowing the Candidate to focus time and energy on acquiring the necessary skills, the Award is an important step in her goal to pursue independent research in neuroimaging of childhood mania.